An Interactive Broadcasting Protocol for Video-on-Demand.pdf

An Interactive Broadcasting Protocol for Video-on-Demand Jehan-Fran?ois Paris Department of Computer Science University of Houston Houston, TX 77204-3475 paris@acm.org Abstract Broadcasting protocols reduce the cost of video-on- demand services by distributing more efficiently videos that are likely to be simultaneously watched by several viewers. Unfortunately, they do not allow the customer to pause, move fast forward or backward while watching a video. We present an interactive pagoda broadcasting proto- col that provides these functions at a very reasonable cost. Our protocol is based on the pagoda broadcasting protocol and requires a set-top box buffer large enough to keep in storage all video data until the customer has watched the entire video. As a result, rewind and pause interactions do not require any server intervention. To minimize the bandwidth requirements of fast forward interactions, the server only transmits the segments that are not available on any of the server broadcasting chan- nels. We evaluate the overhead of these fast forward operations through a probabilistic model. Our data indicate that the most costly fast forward operations are those starting at the beginning of the video and jumping to the beginning of the second half of the video while most fast-forward operation taking place during the second half of the video require little or no additional data. 1. Introduction Despite all the attractiveness of the concept, video-on- demand (VOD) [16] has yet to succeed on the marketplace. The main reason for this lack of success is the high cost of providing video services. As a result, VOD cannot yet compete on a price basis with its two more entrenched rivals, namely pay-per-view and video- cassette rentals. This situation has led to numerous proposals aiming at reducing the cost of providing video-on-demand (VOD) services. Many, if not most, of these proposals have focused on finding ways to distribute the top ten or twenty so-called